#1 Fails is Bullshit  (This was covered on the 1st page of this topic already.)
https://bitcointalk.org/index.php?topic=1709776.msg17135430#msg17135430
https://bitcointalk.org/index.php?topic=1709776.msg17136990#msg17136990

#2 Fails is Bullshit
Between the increased Difficulty, and hard coded checkpoints in the Software, # 2 fails.

#3 An attacker can rent or short +50% of the existing coins without taking any risk (no unrecoverable sunk costs as opposed to PoW)

LMAO ,    the mythical Short attack, which again I call Bullshit!
Anything , stocks or coins PoW or PoS can be Shorted. But you guys always act like it is so easy.
Fact is YOU HAVE TO PUT UP COLLATERAL TO BORROW AGAINST THE SHORT, and if your short attempts fails, (which there are ZERO Guarantees it will Work.) ,
You lost all of your Collateral and failed in your attempt to hurt the coin. (That is when you realize you were STUPID for thinking shorting was easy.)  
Please pick a coin and show us how easy this is to pull off, until then I am calling it BULLSHIT!


 

FYI:
You can tell you don't know much about Proof of Stake,
in your Shorting Myth you say 50% of the existing coins.
Proof of Stake using Coin Age, means you have to have 51% of coin age, not 51% of the coin supply.
You may have 60% of the coin supply, but if the other 40% has a higher coin age, the PoS coin will be able to resist your 51% attack.  
Also the second you start staking , your coin age % starts dropping, so even if you have 51% of the coinage , once you mine 2% only, you are down to 49% and that is the end of your attack. Which is why Proof of Stake is more resistant to 51% attacks than PoW.  

PoW is an Adversarial Consensus System, which is fighting each other using hash rate.

PoS is a Cooperative Consensus System, where we take turns leading the blockchain,
like a group of runners when one gets tire another leads, together we create the Strongest Chain.